Chip breaking drill device



1 -8- ,J. w. KARWEHT CHIP BREAKING DRILL DEVICE Filed Nov. 20, 1942 Hum3 fir INVENTOR.

I Ana/P46) v punch.

Patented Nov. 9, 1948 our? BREAKING DRILL mzvrca John W. Karweit,Skokie, 111., assignor, by mesne assignments, to Ex-Cell-O Corporation,Detroit, Mich., a corporation of Michigan ApplicationNovember 20, 1942,Serial No. 466,273

11 Claims.

The present invention relates to the art of drilling and moreparticularly to twist drilling and to the drilling of elastomers andplastics, as well as metal having stringy characteristics, without theencumbrances of long stringy chips.

In many respects the present invention is an improvement upon theinvention set forth in my co-pending application, Serial No. 455,417,filed August 20, 1942, reference to which is hereby made 'to the extentthat a further understanding of the present invehtion may be pertinentit being understood that th word stringy," used herein, is in keepingwith 'machine shop parlance to identify material that is string-like incharacter, which chips occur with a material ductile enough that ashaving such as a chip progressively cut from the material does notbreak under the cutting strain imposed upon it by a cutting edge fedinto the material.

It is well known that in drilling holes in the conventional manner in anelastomer or plastic, great care has to be exercised to avoid exceedingthe capacity of the flutes in the drill to store cuttings made upon anyparticular feed traverse of the drill into the work. If the storagecapacity is exceeded, or, if a long curly chip becomes impacted in theflutes, the scoring and friction between the wall of the bore and thechip carried by the'drill will cause such friction and heat as to meltor liquefy the chip and/or the wall. If the chip is melted it adheres tothe drill and clogs the flutes. The operator must then take time outfrom the point of the drill, the drill is autoeither to clear the flutesor replace the drill. Furlimits of the cut.

Furthermore, to those familiar with the drilling of an elastomer, suchas a semi-soft or soft rubber out of which bottle corks and vibrationdampeners are made, the hole left by a twist drill is greatly undersizeand the walls of the bore are very shabby. This is due to the fact thatin the conventional process the non-circular cross-section of the drillpermits the rubber to yield inwardly as the flutes pass and to stretchoutwardly to permit the ribs of the drill to pass. Under thesecircumstances the hole never is up to the diameter of the drill and thewalls are scuffed and unsatisfactory.

Because of these difficulties it has been the conventional practice toperforate elastomers either by coring a mold if one hole only is used,or by punching the hole or extra holes with a hollow diameter of thehole varies from one end to the other due to the resiliency of therubber and the action of the material under pressure.

In the present invention instead of maintain- In the. latter instance,obviously the matically lifted a few thousandths of an inch distancefrom the bottom of the hole each time a predetermined cut is made. Thislifts the chip from the body and with the assistance of the leading edgeof the ribs the chip is cut or broken away from the body inv smallenough piecesto clear the flutes. By lifting the chips before they arebroken the action thus provided permits the rubber to return to itsresting position ahead of the drill and the next cut is the same fullcut as all the preceding cuts, thereby providing a uniform diameterthroughout the stock.

When drilling rubber, however, other than that commonly known as hardrubber, a comparatively fast drill rotation has been found to bedesirable. Speeds upwardly of 1.700 R. P. M. had been found to bedesirable. The exact speed depends, of course, upon the peripheral speedof the drill surface in the work which in turn is related directly tothe size of the drill. A small drill is revolved much faster than alarge drill, and the 1,700 R. P. M. mentioned would probably be theoptimum minimum for a drill in diameter, such as a standard drill, highspiral drills permitting faster speeds.

A further advantage with the present invention resides in the fact thatthe drill upon t r n the work piece, such as made of an elastomer orplastic, does not cause a crater-like burr around the mouth 'of the cutnor does it leave a burr around the edge of the cut-when the drill cutsthrough the opposite wall of the work piece as is the case with theconventional drilling of such materials as those mentioned.

A further object of the invention is to provide a new and improvedapparatus forproviding a good wall finish in drilled passageways, whichflnish is free from scores caused by chips in the drill flutes.

A further purpose of the present invention is found in the provision ofmeans for making a hole in the rubber stock by a twist drill in whichthe diameter of the hole is substantially the same size as that of thedrill.

A further object of the invention is to provide an improved apparatusfor .deep hole drilling, a wide range of materials including elastomers,

thermoplastics, stringy metals, wood and ferrous metals. 7

A further object of the invention is to provide an improved continuous,forward feed for twist taper upon the quill spindle, which relationshipis commonly-known as a'standard end taper for inserted shanks, or theupper end. as'shown in Fig. 2, may be provided with a male shank 34adapted to be received in a female tapered opening in the quill spindlein the manner commonly known as the Morse taper Joint, or the third way,the commonly known thread for a Jacobs chuck.

The drive shaft is shouldered as at 35 with. a reduced portion 38 uponwhich is received the innerrace'3l of a frictionless bearing, the outerrace 33 of which is received in a recess 40 with the hollow 33 of theupper member 28. Beyond and shown in section in the embodiment showninFlg. 2; and I Fig. 4 is a side elevationai view of the cam shown inFig. 3. I

As mentioned in my co-pending application, inthe practice of theinvention the drill is preferably reciprocated axially just enough tobreak the chipsonce every revolution of the drill. Although the timing:of Ithe reciprocation may be varied for. every second or third relativerevolution if desired, as by rotating the work or otherwise, theqiiestion of whether or not this is done for any particular design willdepend a great deal upon the size of the chip that can be cleared by theflutes considering the metalbeing machined, and upon the number ofcutting edges upon the drill.. It is preferred that the cuts made by thecutting edges overlap between reciprocations.

The reciprocation mentioned takes place while the continuous feedtraverseis being maintained, either by hand or automatically, it beingintended that the size of the chips be small enough to be sure to clearthe flutes. Then with the vibration set up in the drill by thereciprocations, the chips are constantly agitated in a manner preventingbinding and the agitation operates also to lift the chips out of theflutes.

Referring now to the drawing in further details, the inventionillustrated in Fig. 1 is shown as installed upon a drill press illhaving a casing ll mounted on a standard i2 where, upon one sidethereof, the casing carries a motor l3 which drives through a V-belt H,a spindle l5 Journalled in the casing Ii on the other side of thestandard l2. A quillv i6 is reciprocably mounted in the casing II forfeed and. return movements of the drill I8 and is controlled by themanual throw ll. A quill spindle I9 is carried by the quill. Theembodiment of the invention is shown at as supported upon the bottom ofthe quill spindle i9 andls driven from the drive spindle l5 through thequill spindle I9. At its lower end, the embodiment supports a drillchuck 2| which receives the drill l8.

Below the drill l8 a table 22 is adiustably mounted on the standard l2by means of a split collar 23 and a lock nut 24, with a work piece 25shown as supported upon the table in position to be operated upon by thedrill l3 when the drill is fed downwardly by the manual throw l'l. a

In Fig. 2, the device is shown in sectional detail. A housing comprisingan upper part 28 and a lower part 21 threaded togetheras at 23, encasesthe working parts which include a drive shaft 30, a driven shaft 3|telescoping into the reduced portion 36 the drive member is threaded asat I to receive a nut 42 to hold the inner race 31 tightly in place uponthe drive member. 43 to receive the cam member 32 which comprises acircular washer-like disk as shown in Fig. 3,- which disk will bedescribed in further detail a little later. Between the cam member 32and the outer race 33 a spacer 44 is provided by which the thrust uponthe cam is carried on the outer race 38 through the upper member 23' ofthe housing 20.

The lower end 45 'of the drive member 30 is provided with an axial boretherein and longitudinally disposed slots 41 through the well thereofthat are located diametrically, opposite each other. I

The upper end of the driven shaft 3| is ground to a cylindricalouter-contour l3 and provided with openings receiving the transverseshaft iil therein that is heldin place by a pin 52. The bore 48 on thedrive member is also ground to a close clearance to receive thecylindrical portion of the driven member 3| in a closely fittedreciprocal relationship. The shaft II is disposed in the slots 41 whichare provided with suilicient length to permit substantial relative axialmovement between the drive and driven members.

At its lower end the driven shaft 3! is threaded as indicated at 53 toreceive the shuck 2|, such as a Jacobs chuck, in which is mounted thedrilll8. s From the description thus far, it will be seen that as theshank 34 is rotated by the quill spindle l9, rotation is imparted to thedriven member-3| the drive shaft 30 for'mutual alignment, a cam memberalso axially reciprocable in the bore 43.

The ends of the shaft Ii are reduced in diameter as at 34 to receivea-washer 35' against a shoulder 56 and also needle bearings 51 thatsupport a roller follower II in position to cooperate with the cam 32.The needle bearings'and rollers are held in place by a pinand washerassembly The lower end 45 of the drive shaft 33 ls lournalled withrespect to the lower member 33 by a frictionless bearing-M held in placeby lock screws 62. In a recess 63 below the frictionless bearing iii aconventional grease seal '84 Ma well known type is installed to preventthe escape from inside of the housing 23.

A spring 65 is disposed between the-inner race 66 of the frictionlessbearing 3| and a washer 31 that rests against the shaft II. The springCI is a compression spring and acts to hold the driven shaft 3| in itsupper position and to maintain contact between the cam follower rollersll and the cam member 32.

It will be noted that the. cam follower rollers are identical,preferably for inventorypurposes, and at one end thereof they areprovided with an The upper member is enlarged as at Y of grease definedby the treads of both rollers are spaced i "radially from each otherupon the cam surface.

Asaviewed in Fig. 2, the tread HI upon the roller at the right followsthe greater circle, whilethe tread upon the roller at the left follows acircular path of smaller diameter. Y Referringnow to Fig. 3, the path onthe cam followed by the tread of the right hand roller includes adepression 1 I, while the path of smaller diameter'includes a depressionllwhich depressions are disposed diametrically opposite each other inthe face of the cam. These depressions H and 12 are of the same depthand of the same angular length so that when the tread of one rollerrolls into its respective depression the tread of the other roller rollsinto its respective depression simultaneously, thereby maintaining abalanced effort and cam action upon opposite sides of the drive anddriven members. i

The balancing of the cam effort upon both sides of the drive and drivenmembers and the provision of a telescoping relationship upon groundsurfaces provides for a true running dril1 and long life under anyand'all working conditions within the expected operation of theembodiment.

It will also be observed in connection with Fig. 3, that the dottedlines 13 and IL-are shown which correspond in planview with thedepressions II and 12. The lines 13 and 14 indicate like cams upon theopposite side of the cam member 32, the

depressions upon the opposite faces of the cam member being differentonly in the depth to which the depression is ground. Thus with finedrills or light feeds or high speeds of rotation of the drill theshallower pair of the two cam surfaces may T a r a off and withoutdahger of frictional conditions arising that would cause a scoring ofthewali of the cut.

comparatively. speaking, it is also of interest to note that the camdepth should be such in the apparatus shown that any. particular drillworking at its best feed rate. will be lifted enough to break the chipthat it is cutting while that .feed rate is being maintained. The moreshallow cams will be used with the smaller drills and the deeper camswill be used with the larger drill sizes. sive tables, the criterionused is to determine the bestfeed rate for any drill in any particularmaterial and then select the cam which will assure the breaking of thechip without excessive drop or vibration. For instance, if a numberlfidrill is being used in amaterial with a feed rate-of .015 of an inch perrevolution, the cam depth .015 of an inch feed is lost during thatangleof rotation when the camis in operation. ,The optimum cam depth forany given drill isone "which will break the chip clean betweensuccessive cuts. In connection withrubber this cam lengths is availablein the operation of the embodlment described.

In order to maintain the housing 20 stationary, a C clamp ring 15 issecured tothe housing and provided with an outrigger arm I6 adapted toengage and slide up and down the support l2 during the feed movement .ofthe drill i8. In this way the cam is held against rotation while therollers rotate with the drive and. driven mem- If used with suchmaterials as elastomers and.

plastics having a low melting point, the fluid also assists in floatingthe chips up through the flutes as well as assuring cool cuttingconditions. It is important to note that with a chip of a size smallenough to clear the flutes there is littleis a little greater, having inmind the elasticity of the .rubber and with elastomers and plastics thecam depth is also generally greater than that used with metal, asdescribed in my co-pending application. Any increase in cam depth .toassure the breaking of such material, creates a slightadditionsvibration factor which is favorable in assisting t clear the fiutesofthe-chips. Because of this. the tolerances are wider and safer upon theside having a cam depth greater than that needed.

Thus, it will be apparent to those skilled in the art that variouschanges and combinations of the parts can be made'without departing fromthe spirit of the invention the scope of which is commensurate with theappended claims.

The claims of the present application cover a species subordinate to thesubject matter disclosed and claimed in my c'o-pending applicationSerial No, 484,612, filed April 26, 1943.

Whatis claimed is:

l. A combination driller and chip breaker including a non-rotary member,a drive shaft and a driven shaft rotatably mounted with respect to saidmember and reciprocally mounted with respect to one another, a cam meanssupported upon 'said member and having concentric tracks each tracks,said cam means and follower means carrydanger of the chips becomingimpacted in the flutes and damming the-cooling fluid from the .lowerportions of the out. Therefore, #the cooling fluid is able to flow downthe flutes and reach the end of the tip without danger of being cut ingthe axial thrust load between the shafts incurred during the feedtraverse thereof, means urging said cam means and follower means incontinuous contact with each other, said cam means, follower means andurging means imparting a reciprocation to the driven shaft once eachrotation of the driven shaft which reciprocation is accomplished withinapproximately 60 of rotation, and means upon said driven shaft forsupporting a metal cutting drill in work engaging position, saidreciprocation com'minuting the chips formed by the drill.

In this connection, without giving extendriven shaft member disposed onan axis projecting'through said supporting member and adapted "of therollers is formed with a a porting member out of I ing flrst,a reliefstroke followed by a return stroke through a small fraction of an inch.to

efl'ect termination of a chip being formed by, the

drill when cutting. i

5. A device according to claim 4 in which each the enlarged tread on oneend portion, and is adapted to be reversed end for end, on thediametrlcal shaft so as to normally sustaining said shaft member against1" the axial drilling thrust, one of 'said elements being carried bysaid supporting member in fixed axial position relative thereto, theother of said elements being supported fromsaid shaft member inopposed-relation to said one element, and being operatively connected tosaid shaft member'for rotary drive therefrom, said cam element defininga circular track extending concentrically, about said axis and formedwith alternating dwell and relief areas, said follower elementcomprising a roller having a diametrically enlarged tread contacting andrelatively movable along said track, said elements being operable byreason of said dwell and relief areas at least once during each relativerevolution therebetween and each'time gs within a minor portion of saidrevolution, to"

effect an axial reciprocation of said shaft member with respect to saidsupporting member out of normal position comprising first a reliefstroke followed by a return stroke through a small fraction of an inchto efl'ect termination of a chip being formed by the drill when cutting.

3. A device according to claim 2 in which said cam element has pluralityof circular tracks extending concentrically about said shaft member andeach formed with alternating dwell and relief areas, and, said followerelement comprising a plurality of rollers each with a diametricallyenlarged tread respectively in rolling contact with said tracks.

4. A device. for drilling machinable material comprising, incombination, a supporting member adapted to be mounted for cutting feedmovement and to be constrained against rotacomprising,

casing adapted to be mounted for cutting feed locate the treadselectively for rolling contact with either one of the concentrictracks. J

6. A- devi e for drilling machinable materiel combination, a hollowsupporting mpvement and to be constrained against rotation andcomprising two opposite end sections removably secured together; adriven shaft member journalled in and projecting from one endof saidsupporting casing and being adapted'for connection for rotary powerdrive and for limited independent axial movement relative to said sup:porting ,casing, said shaft-member being adapted to support a fluteddrillaat the outer endJn coaxial relationithereto and for rotaryandaxial movement therewith, and relatively revoluble coacting cam andcam follower elements for normally s'ustainlng'said shaft member-againstthe axial drilling thrust, the cam element comprising a flat annular camplate having on one side face a track for'med with alternating dwell andrelief areas and extending concentrically about said shaft member; saidplate being rigidly clamped in position between said casing sections,the follower element being supported from said shaft member in opposedrelation to said cam element,

and being operatively connected to said shaft member for rotary drivetherefrom, said elements being operable by reason of said dwell andrelief areas at least once during each relative revolution therebetweenand each time within a minor portion of said revolution, Q effect anaxial retion, a driven shaft member disposed on an axis projectingthrough said supporting member and adapted to be connected for rotarypower drive and for limited independent axial movement relative to saidsupporting member, said shaft member being adapted to support a fluteddrill at one end in coaxial relation thereto and for rotary and axialmovement therewith, and relatively revoluble coacting cam and camfollower elements for normally sustaining said shaft member against theaxial drilling thrust, the cam element comprising an overhead circularend face cam carried by said supporting member in fixed axial positionrelative thereto and defining two inner v and outer concentric camtracks extending con-- centrically about said axis and each track formedgo with alternating dwell and relief areas, the follower element beingsupported from and operatively connected for rotary drive to said shaftmember and comprising a diametrical shaft extending through said shaftmember for moveas tively. along said tracks, said elements being opermable by'reason of said dwell and relief areas at least once during eachrelative revolution therebetween and each time within a minor portion ofsaid revolution, to'effect anQaxlal reciprocation cimocation of saidshaft member with respect to sad supporting casing out of normalposition comprising first a relief stroke followed by a return strokethrough a small fraction of an inch normal position comprls- I to effecttermination of a chip being formed by the drill when cutting.

7. 'A device according to claim 6 in which the I cam plate also has onthe other side face a track extending concentrically about the shaftmember and formed with alternating dwell and relief areas, said lastmentioned dwell and relief areas differing dimensionallyfrom the dwelland relief areas on the opposite side face of the plate, and in whichthe cam plate is reversible between the casing sections, whereby tolocate either side face of the cam plate selectively inoperativeposition for coaction with the follower element.

8. A device for drilling machinable material comprising, in combination,a supporting member adapted to be mounted for cutting feed movement andto be constrained against rotation, a

driven shaft member disposed on an axis pro- Jecting through saidsupporting member and adapted to be connected for rotary power drive andfor limited independent axial movement relative to said supportingmember, said shaft ment-'- ber' being adapted to support a fluted drillat one end in coaxial relation thereto and for rotary and axial movementtherewith, and relatively revoluble coacting cam and cam followerelements for normally sustaining said shaft member against the axialdrilling thrust, one ofsaid elements be ing carried by said supportingmember in fixed of said shaft member with respect to said supaxialposition relative thereto, the other of said,

7 elements being supported from said shaft member in opposed relation tosaid one element, and

being operatlvely connected to said shaft memextending concentricallyabout the shaft member.

each track being formed with alternating dwell and relief areas, saidcam plate being reversible side for side selectively to locate eithercam track in operative position for coaction with the follower element,said elements being operable by reason of the dwell and relief areas ofeither track at least once during each relative revolution therebetweenand each time within a minor portion of said revolution, to effect anaxial reciprocation of said shaft member with respect to said supportingmember out of normal position comprising first a relief stroke followedby a return stroke through a small fraction of an inch to effecttermination of a chip being formed by the drill when cutting,

9. A device for drilling machinable material comprising, in combination,a supporting member adapted to be mounted for cutting feed movement andto be constrained against rotation, a driven shaft member disposed on anaxis projecting through said supporting member and adapted to beconnected for rotary power drive and for limited independent axialmovement relative to said supporting member, said shaft member beingadapted to support a fluted drill at one end in coaxial relation theretoand for rotary and axial movement therewith, and relatively revolublecoacting cam and cam follower elements for normally sustaining saidshaft member against the axial drilling thrust, one of said elementsbeing carried b said supporting member in fixed axial position relativethereto. the other of said ele-' ments being supported from said shaftmember in opposed relation to said one element, and being operativelyconnected to said shaft member for rotary drive therefrom, said camelement defining I two circular tracks extending concentrically aboutsaid axis each formed with alternating dwell and relief areas, saidfollower element comprising two rollers, each having a diametricallyenlarged tread on one end portion andcontacting and relatively movablerespectively along said tracks, each roller being reversible in positionend for end so as to locate its tread selectively for rolling contactwith either one of said tracks, said elements being operable by reasonof said dwell and relief areas at least once during each relativerevolution therebetween and each time within a minor portion of saidrevolution, to eflect an axial reciprocation of said shaft member withrespect to axial sup-' porting member out of normal position comprisingfirst a relief stroke followed by a return stroke througha smallfraction of an inch to effect termination of a chip being formed by thedrill when cutting.

10. A device for drilling metal and the like comprising, in combination,a hollow casing having opposite end sections connected together, andadapted to be supported for axial feed movement and to be constrainedagainst rotation, anlannular cam disk rigidly clamped coaxially betweensaid sections and having an and cam face formed into two concentricradially spaced cam tracks, each with a flat arcuate depression thereinextending over a minor portion of the circumferl0 ence. the depressionsof said tracks being diametrically oppositely disposed and eachextending through the same angular degree, adrive shaft extending fromone end of said casing through and iournalled in anti-friction bearingsin said end sections and extending axially through said disk, a drivenshaft extending from the otherv end of said casing telescopically intosaid drive shaft for relatively axial shifting movement, a diametrlcalshaft extending through and fixed in,

said driven shaft, said driven shaft being formed with longitudinalspline slots in its wall at dia metrically opposite sides and theopposite ends of said diametrical shaft projecting slidably through saidslots, two cam follower rollers removably mounted respectively forrotation on opposite ends of said diametrical shaft in position forrolling contact respectivelywith said tracks, and coiled compressionspring means encircling said drive shaft and seated in said casing andacting on said diametricai shaft in a direction to urge said drivenshaft inwardly and to maintain said rollers in contact with said tracks,each of said rollers having a diametrically raised tread on one endportion, and being reversible end for end to locate said treadselectively in registration with one or the other of said tracks,whereby upon each revolution of said rollers, said driven shaft iscaused to reciprocate axially in an inward retract movement and outwardreturn movement within a minor portion of said revolution through adistance determined bythe depth of said depressions sufliciently toterminate the chips being formed by the drill when drilling.

11. A drilling assembly for use in the art of metal drilling comprisinga housing, a driven shaft Journalled in the housing. a cam deviceincluding a member having two concentric paths thereon each with asingle relief occupying an arc of approximately 60, a follower devicecooperating with said cam device and including a rotor for each pathhaving a flange thereon, said rotors being located at diametricallyopposite positions and at difl'erent radial distances from the axis of45 rotation of the driven shaft,one of said devices being carried by thehousing, and the other of said devices being carried by the drivenshaft;

means for inducing a constant engagement between said devices, and meansfor mounting a drill 50 upon the outer end of said driven shaft inoperative position, said devices cooperating with each other to impartto the drill a retractive' reciproc'ation once each revolution of thedrill to comminute the chips formed by the drill.

' JOHN W. KARWEIT.

REFERENCES CITED The following references are of record in the file ofthis patent:

